Is there anything that would change really between the two?

The 1994 engine would be replacing the same displacement engine in a 1988 truck. The 94 is hooked up to an automatic, while the 88 is a standard

Wiring or exhaust or anything that would change that anyone knows about, I haven't found anything saying they are different at all.

 

sensors and electronics/ harnesses are different. Use it as a long block and swap over all efi related items, Injectors, sensors, etc. I would go out and get a new knock sensor harness and swap over the complete intake manifolds with all the sensors attached, and swap over the harness.

 

The 1988 was different from all the others.I can`t remember why but I do remember that it was the first year and for some reason they changed it after only one year.I am also thinking your motor mounts will be different.I had a time getting motor mounts to fit mine and finally ended up just cutting one and rewelding it.Do some research and good luck.